var myChart8 = echarts.init(document.getElementById("container7"));
var app = {};
option8 = null;
option8 = {
    title: {
        text: '八号线',
        left: 'center'
    },
    series: [
        {
            name: '电压',
            type: 'gauge',
            detail: { formatter: '{value}V' },
            data: [{ value: 220}],
            min: 200,
            max: 250,
            splitNumber: 5
        }
    ]
};

setInterval(function () {
    option8.series[0].data[0].value = (Math.random() + 220).toFixed(1) - 0;
    myChart8.setOption(option8, true);
}, 2000);
;
if (option8 && typeof option8 === "object") {
    myChart8.setOption(option8, true);
}